Editing Anemia (section)

====Macrocytic====
{{main|Macrocytic anemia}}
* [[Megaloblastic anemia]], the most common cause of macrocytic anemia, is due to a deficiency of either [[vitamin B12|vitamin B<sub>12</sub>]], [[folic acid]], or both.<ref>{{cite journal |last1=Long |first1=Brit |last2=Koyfman |first2=Alex |title=Emergency Medicine Evaluation and Management of Anemia |journal=Emergency Medicine Clinics of North America |date=August 2018 |volume=36 |issue=3 |pages=609–630 |doi=10.1016/j.emc.2018.04.009 |pmid=30037447 }}</ref> Deficiency in folate or vitamin B<sub>12</sub> can be due either to inadequate intake or [[malabsorption|insufficient absorption]]. Folate deficiency normally does not produce neurological symptoms, while B<sub>12</sub> deficiency does.
** [[Pernicious anemia]] is caused by a lack of [[intrinsic factor]], which is required to absorb vitamin B<sub>12</sub> from food. A lack of intrinsic factor may arise from an [[autoimmune]] condition targeting the [[parietal cell]]s (atrophic gastritis) that produce intrinsic factor or against intrinsic factor itself. These lead to poor absorption of vitamin B<sub>12</sub>.
** Macrocytic anemia can also be caused by the removal of the functional portion of the stomach, such as during [[gastric bypass]] surgery, leading to reduced vitamin B<sub>12</sub>/folate absorption. Therefore, one must always be aware of anemia following this procedure.
* [[Hypothyroidism]]
* [[Alcoholism]] commonly causes a [[macrocytosis]], although not specifically anemia. Other types of [[liver disease]] can also cause macrocytosis.
* Drugs such as [[methotrexate]], [[zidovudine]], and other substances may inhibit [[DNA replication]] such as [[heavy metals]]
Macrocytic anemia can be further divided into "megaloblastic anemia" or "nonmegaloblastic macrocytic anemia". The cause of megaloblastic anemia is primarily a failure of DNA synthesis with preserved RNA synthesis, which results in restricted cell division of the progenitor cells. The megaloblastic anemias often present with neutrophil hypersegmentation (six to 10 lobes). The nonmegaloblastic macrocytic anemias have different etiologies (i.e. unimpaired DNA globin synthesis,) which occur, for example, in alcoholism.
In addition to the nonspecific symptoms of anemia, specific features of vitamin B<sub>12</sub> deficiency include [[peripheral neuropathy]] and [[subacute combined degeneration of the cord]] with resulting balance difficulties from posterior column spinal cord pathology.<ref>[http://www.emedicine.com/NEURO/topic439.htm eMedicine – "Vitamin B-12 Associated Neurological Diseases": Article by Niranjan N Singh], July 18, 2006. {{webarchive|url=https://web.archive.org/web/20070315044706/http://www.emedicine.com/neuro/topic439.htm|date=2007-03-15}}.</ref> Other features may include a smooth, red tongue and [[glossitis]].
The treatment for vitamin B<sub>12</sub>-deficient anemia was first devised by [[William Murphy (scientist)|William Murphy]], who bled dogs to make them anemic, and then fed them various substances to see what (if anything) would make them healthy again. He discovered that ingesting large amounts of liver seemed to cure the disease. [[George Richards Minot|George Minot]] and [[George Whipple]] then set about to isolate the curative substance chemically and ultimately were able to isolate the [[vitamin B12|vitamin B<sub>12</sub>]] from the liver. All three shared the 1934 [[Nobel Prize in Physiology or Medicine|Nobel Prize in Medicine]].<ref>{{cite web|url=http://nobelprize.org/nobel_prizes/medicine/laureates/1934/press.html |title=Physiology or Medicine 1934 – Presentation Speech |publisher=Nobelprize.org |date=1934-12-10 |access-date=2010-08-24| archive-url= https://web.archive.org/web/20100828134134/http://nobelprize.org/nobel_prizes/medicine/laureates/1934/press.html| archive-date= 28 August 2010 <!--DASHBot-->|url-status = live}}</ref>